1. Field of the Invention
The present invention relates to a plating apparatus for plating a surface of a workpiece to be plated or substrate such as a semiconductor wafer or the like, and more particularly to a plating apparatus for forming a plated film in fine interconnect trenches, holes or resist openings defined in a surface of a semiconductor wafer, or forming bumps (protrusive electrodes), which are to be electrically connected to package electrodes or the like, on a surface of a semiconductor wafer. The present invention is also concerned with a plating apparatus for filling via holes to form a number of through via plugs in a substrates such as a semiconductor wafer, an interposer, or a spacer for use in three-dimensional packaging for semiconductor chips or the like. More specifically, the present invention relates to a plating apparatus for plating substrates that are held by substrate holders to be immersed in plating tanks.
2. Description of the Related Art
A plating apparatus, which is configured to plate substrates that are held by substrate holders and vertically immersed into the plating solution in a plating tank, is known. Before the plating apparatus starts to operate, the substrate holders are stored in a substrate holder stocker. When the plating apparatus starts to operate, the substrate holders are removed from the substrate holder stocker one by one. Then, the substrate holders hold semiconductor wafers to be plated. The substrate holders, which are holding the semiconductor wafers, are transported by a substrate holder transporter successively to a plating tank where the semiconductor wafers are to be plated and various processing tanks where the semiconductor wafers are to be processed.
The conventional plating apparatus include a plating apparatus having a plurality of plating tanks and plating solution circulating tanks for circulating a plating solution through the plating tanks to plate workpieces therein (see, e.g. Japanese laid-open patent publication No. 5-339794). Specifically, the plating tanks and the plating solution circulating tanks are interconnected, respectively. The plating tanks are supplied with the plating solution from the corresponding plating solution circulating tanks, and the plating solution that has flowed back from each of the plating tanks is returned to the other plating solution circulating tanks than the corresponding plating solution circulating tank, thereby uniformizing the components of the plating solution.